This is a curtain wall anchor. Two field arc welds joined the thin anchor clip to the thick shim. The excess power has burned the thin clip but only slightly penetrated the shim. Then the mechanical stresses separated those two elements. The problem is minor because this is a temporary weld only but there is a safety concern. The hot sparks melted into the surface of mullion coating but this area is hidden from view behind the firestop so this is negligible.